EF4 Code First: how to add a relationship without adding a navigation property

Question

How should I define relationships using Code First but without using any navigation properties?

Previously I have defined One-Many and Many-Many by using navigation properties in both ends of the relationship. And the appropriate relationships are created in the database. here's a stripped down version of how the classes look like (I've converted the Many-Many relationships to one-many for simplicity).

public class User 
{
    public string UserId { get; set; }
    public string PasswordHash { get; set; }
    public bool IsDisabled { get; set; }
    public DateTime AccessExpiryDate { get; set; }
    public bool MustChangePassword { get; set; }

    public virtual Role Role { get; set; }
}

public class Role
{
    public int RoleId { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }

    public virtual ICollection<User> Users { get; set; }
    public virtual ICollection<Right> Rights { get; set; }
}

public class Right
{
    public Guid RightId { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }

    public virtual Role Role { get; set; }
}

However, if I remove the navigation properties, no relationships are being created. Here's how the classes would look like.

public class User 
{
    public string UserId { get; set; }
    public string PasswordHash { get; set; }
    public bool IsDisabled { get; set; }
    public DateTime AccessExpiryDate { get; set; }
    public bool MustChangePassword { get; set; }

    public int Role RoleId { get; set; }
}

public class Role
{
    public int RoleId { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }
}

public class Right
{
    public Guid RightId { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }

    public int RoleId { get; set; }
}

notice that instead of a navigation property, I have the primary key of the related table. Everything gets created on the table - except the relationship. So how do I get about doing this?

BTW, I've tried various combinations in the OnModelCreating method of the dbcontext but to no avail. Any help is much appreciated!

Thanks, Mel

Answer 1

I believe you always need navigation property on at least one side when using code-first. Then you will be able to map it:

public class User  
{     
    public string UserId { get; set; }     
    public string PasswordHash { get; set; }     
    public bool IsDisabled { get; set; }     
    public DateTime AccessExpiryDate { get; set; }     
    public bool MustChangePassword { get; set; }      
    public int RoleId { get; set; }
    public Role Role { get; set; }
}  

public class Role 
{     
    public int RoleId { get; set; }     
    public string Name { get; set; }     
    public string Description { get; set; } 
}  

public class Right 
{     
    public Guid RightId { get; set; }     
    public string Name { get; set; }     
    public string Description { get; set; }      
    public int RoleId { get; set; }
    public Role Role { get; set; }
} 

public class TestContext : DbContext
{
    public TestContext() : base("Entities")
    {}

    protected override void  OnModelCreating(System.Data.Entity.ModelConfiguration.ModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);

        modelBuilder.Entity<User>()
            .HasRequired(r => r.Role)
            .WithMany()
            .HasForeignKey(r => r.RoleId);

        modelBuilder.Entity<Right>()
            .HasRequired(r => r.Role)
            .WithMany()
            .HasForeignKey(r => r.RoleId);
    }
}

Answer 2

You can use the fluent api to add the relationship, though the "configuration" code is separate from the entity code making it less discoverable.